上颌磨牙牙尖斜面中在正中时无接触的是()
A.舌尖的颊斜面
B.舌尖的舌斜面
C.颊尖的颊斜面
D.颊尖的舌斜面
E.斜嵴的近中斜面
参考答案:C
They _____ TV at this time last night. [ ]
A. was watching
B. were watching
C. watched
D. watch
GB/T380《石油产品硫含量测定法(燃灯法)》试验前,应注意将吸收器、液滴吸收器及烟道仔细用蒸馏水洗净,灯及灯芯应用分析纯()洗涤并干燥。
A.乙醇
B.石油醚
C.苯
D.正庚烷